System for the remote operation of power plants



4 Aug..ll, 1936.

E. PEARSON O 2,050,373 SYSTEM FOR THE REMOTE OPERATION OF POWER'PLANTS Original Filed July 6 1951 s Sheets-Shet 1 LOAD c5114 (BA G'LA 1054 A AA .E'C EC: 1 923 9 Elma/Maw, 103s .E'ijck Beazigoiw,

Guam; 1

Aug. 11, 1936.

E. PEARSON 2,050,373

SYSTEM FOR THE REMOTE OPERATION OF POWER PLANTS OriginaIFiled July 6, 1931 '3-sheets-Sheet 2 iar- J CBB g M mm 928 Ezckfeargon axiom c Aug. 11, 1936. E, PEAR ON 1 2,050,373

SYSTEM FOR THE REMOTE OPERATION OF POWER PLANTS Original Filed July 6, 1931 3 Sheets-Sheet 3 l tgo Z c 771 AF? SE1 SP4 SFS ! REMOTE Comm-o4 Ecc'ck Eeangan,

Gamma 14" Patented Aug. 11, 1936 PATENT OFFICE SYSTEM FOR THE REMOTE OPERATION OF POWER PLANTS Erick Pearson, Chicago, Ill.

Application July 6, 1931, Serial No. 548,906 Renewed November 2, 1935 9 Claims.

My invention relates to power plants and to apparatus for the operation thereof and has for an object to provide a system whereby a plurality of electrical units may be operated or controlled from a single device.

Another object of the invention resides in providing a system in which a plurality of generators may be successively synchronized through a single synchronizer.

An object of the invention resides in providing a system in which the governors of a plurality of generators may be individually adjusted through a single control apparatus.

Another object of the invention resides in provi-ding a system in which the voltage of a plurality of generators may be regulated through a single voltage regulator.

A feature of the invention resides in providing a system in which the control of the generator is accomplished through a pair of centrifugal devices operating in unison with one another.

An object of the invention resides in providng a system in which the synchronizing mechanism is rendered operable when the two centrifugal devices reach predetermined relative positions.

Another object of the invention resides in providing a plurality of generators with separate exciters therefor and in providing a single voltage regulator for procuring the same potentials at said exciters to maintain predetermined voltages for both generators.

Another object of the invention resides in providing a resistance in series with the exciter field coil and providing a switch for shunting said resistance and in further providing a potentially operated device for opening said switch after the potential of the exciter reaches a predetermined value to cause the positive building up of the exciter.

Another object of the invention resides in providing means including a switch for connecting the eXciter to the potential regulator when the generator unit has been connected to the distribution system.

An object of the invention resides in providing a system including a plurality of generators, each having an exciter and in further providing a sin gle voltage regulator therefor adapted to simultaneously regulate the voltages of all of said generators in accordance with the potential of the distribution system.

Another object of the invention resides in providing means for disconnecting any of the generators from the voltage regulator upon disconnection of said generator from the distribution systerm.

A still further object of the invention resides in providing a protective device in which closure of the circuit breaker is prevented in the event that the exciter fails to build up and in which the circuit breaker is opened in the event that the exciter voltage drops below a predetermined value.

An object of the invention resides in providing in combination With a distribution system, a plurality of generators having a. plurality of exciters and a common bus for connecting said exciters in parallel and in still further providing means for connecting said exciters to said bus upon connection of said generators to the distribution system.

Another object of the invention resides in pro viding an over speed switch operated by the generator and a power switch adapted to be operated by the generator line and in further providing means controlled by said switches for regulating the gate opening of the generator turbine, said switches serving to bring the generator back to no load speed in the event the speed of the generator should accidentally exceed a predeter- 2O novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/ or described.

In the drawings:

Figs. la, 11) and 10 together comprise a wiring diagram of a system illustrating an embodiment of my invention.

In the drawings, a system has been shown comprising a power plant feeding a distribution line DL comprising the three phase conductors l, 2, and'3. In this system, two generators and. 15| areemployed; the generator 750 is provided with an armature 152 and a field coil T53 and the generator 15! is providedwith an armature T54 and a field coil 755. The armature 152 is connected to a generator line GLA having phases l, 2 and 3, while the generator 'l5l is connected to a generator line GLB having phases I, 2 and 3. The generator line GLA may be connected to the distribution line DL through a circuit breaker CBA while the generator line GLB may be connectedto the distribution line through a circuit breaker CBB. The circuit breaker CBAis provided with a coil CBAI and with five normally open switches CBAZ, CBA3, CBA4, CBA5 and CBAB. The circuit breaker CBB is constructed with a coil CBB! and with five normally open switches CBB2, CBB3, CBBQ, CBB5, CBB6 and with a normally closed switch CBBl.

The generator we is provided with a governor it? which may be of ordinary construction and which is adapted to control the speed of the prime mover (not shown) which is connected with said generator and to further control the load taken by the generator. Governor l5l' is of the centrifugal type having flyballs acting against a spring to open and close one or more control Valves through which the gate governing the flow of water to the turbine is regulated to deliver the desired amount of power to the generator and to control the speed of the turbine. The regulation of the gate is effected through oil or some other suitable fluid under pressure as is customary and the initial operation of the governor takes place upon the opening of a suitable valve in the oil line. For the purpose of illustration, the oil line has been indicated at It! and the valve therein at I82. The governor spindle for rotating the flyballs may be operated in any suitable manher as by a mechanical drive from the prime mover or generator when the governor is closely positioned or through an electric motor or other source of power when desired. Such construction and the construction of the governor being well known in the art and as illustrated in my co-pending application for patent Serial No. 481,- 948 has not been described and illustrated in detail in this application. The governor is provided with a centrifugally operated switch F58 which is adapted to close when the speed of the governor reaches a predetermined value. This switch may be controlled from the governor spindle operating the fly balls or from any other source of rotary motion rotating in synchronism with or at a speed proportioned to that of the generator.

A starting solenoid 865 is employed which operates the valve W2. When this solenoid is energized the valve M2 is opened and the governor subjected to the oil under pressure controlled thereby, the gate may then be regulated in response to the action of the fiyballs of the gov ernor.

A reversible motor Bill further operates upon the spring of the governor to vary the pressure exerted by the same on the fiyballs, said motor serving to increase the pressure when rotated in one direction and to decrease the pressure when rotated in the other direction.

In a similar manner a governor 759 is employed for the generator 'l5l which governor is provided with a switch l6!) similar to the switch l58. This governor is also provided with a starting solenoid 808 including an oil valve Hi3, and a reversible motor 8m.

Operating in conjunction with the generator l5ll, is a transfer relay XA which includes a coil KM and seven normally open switches XAZ, XA3, XA4, XAl'l, XA6, XAl and XA8 and a normally closed switch XAQ. This generator is further provided with a master relay MA which comprises a coil MAE, and four normally open switches MAZ, MAS, MA and MAB. The generator 15! is likewise provided with a transfer relay XB which comprises a coil XBl, seven normally open switches X132, XB3, XB l, X185, XBB, X31 and X138 and one normally closed switch XB9. A master relay MB is also utilized with generator l5l. This relay comprises a coil MBl, and three normally open switches M132, MB3, MB4.

Each of the two generators is provided with its own exciter, the exciter for the generator 159 being designated by the reference numeral 16! and the exciter for the generator 15! being designated by the reference numeral 162. These exciters may be directly operated from the prime mover for the generator or may be operated in any other suitable manner, if desired. The exoiter l6l comprises an armature 962, a series field coil H53 and a shunt field coil F64. The other exciter I62 comprises an armature 65, a series field coil E66, and a shunt field coil lfi'i.

Current for operating the various apparatus used in conjunction with the invention at the substation is procured from two single phase transformers Hi8 and 76%, said transformers having primaries and ill and secondaries l'l2, and T13. The primaries llll and ill of these transformers are connected to the three phases l, 2, and 3 of the distribution line through conductors 8%, 899 and 892. The two secondaries 172 and N3 of these transformers are connected together and to a common bus and are further connected to busses H6 and ill.

The control line for operating the power plant by remote control is designated by numerals H78 and H9 and may procure energy from any suitable source. Inasmuch as the control apparatus may be operated either by direct current or by alternating current, the source of electric energy 0 for this line has not been shown.

Operating in conjunction with the two generators lfil! and l5l is a single synchronizing device indicated in its entirety at 845 and a single voltage regulating device llill which will be subsequently described in detail and which may be used in conjunction with either or both of the generators as will later more fully appear.

The exciter lfil is connected to the generator lfifl as follows. The series coil E63 of exciter lfil is connected to the armature 952 thereof through a conductor 582. This coil is further connected through a conductor i183 with the shunt coil 164, said conductor being in turn connected to another conductor M4 which leads to the field coil 753 of generator 15B. The other side of the field coil E53 of generator 158 is connected through a conductor 185 with a rheostat 186 which in turn is connected through a conductor l8? with the other side of the armature 962 of exciter 16!. By regulating the rheostat we the desired voltage may be had across the field ?63 of the generator.

In a similar manner the field coil 1% of the exciter 162 is connected through a conductor 783 with the armature T65 of said exciter. Conductor 789 connects the series coil [66 to the shunt coil lfil and is itself connected to another conductor 190 which in turn is connected to the field coil 156 of generator l5l. The other side of the field coil 156 is connected through a. conductor l9! with a rheostat 1192 similar to the rheostat Z85. This rheostat is connected through a conductor 193 with the other side of the armature 'l65 of exciter 762.

In the event that the master relay is open due to various failures detected by any of the protective devices to be subsequently explained, it becomes undesirable that the master relay be again connected after the correction of the failure. To prevent such re-connection of the apparatus, tWo relays AA and AB are employed which I have termed anti-start relays, which relays are operative to prevent the closing of the master relays MA and MB, except by manual means at the control station. The relay AA comprises a coil AAI, a normally closed switch AA2, and a normally open switch AA3. The relay AB comprises a coil AB], and a normally closed switch AB2. This relay is a time controlled relay and is provided with a dash pot AB3 or similar equivalent which prevents the opening of the switch AB2 until a. predetermined time has elapsed after the relay AB has been energized.

The two relays MA and MB are energized from the control circuit 118 and 119 as follows. The control line H9 is connected to two switches, 208 and 798. The operation of the master relay MB is controlled through the switch 198 while the operation of the master relay MA is controlled through the switch 288. The master relay MA governs the operation of generator 758 while master relay MB governs the operation of generator 55!.

The various circuits controlled by relay MB will be first described in detail. A bus E98 is connected to the side T58 of the control line. Switch I93 is connected through conductor I9! with coil AB! of relay AB, which coil is further connected to bus Z98. Conductor i9? is also connected to switch ABE of relay AB which in turn is con nected through a conductor 189 to switch MB2. Conductor '598 is further connected to another conductor which in turn is connected with coil MBi which in turn is connected through conductor 883 with the bus 196.

Upon closing switch 198 two circuits are established, the one being through the coil ABI of relay AB and the other being through the coil MB! of relay MB. The relay AB being a timed relay does not open switch ABZ until after the lapse of a predetermined length of time. During this time the relay MB is given an opportunity to close. If said relay does not close within this length of time. switch ABZ opens and the circuit through the coil MB! of relay MB is broken. Thereafter said relay cannot be closed unless the switch 198 is manually operated to cause the relay AB to be re-set. If however everything is in proper condition, coil MB! operates relay MB and the various switches MBZ, MB3 and MR4 thereof are closed. As soon as relay MB is operated, the circuit through the coil MB! thereof is maintained through the switch MB2. This switch is connected through a conductor 804 with conductor I89 thereby shunting switch ABZ. After relay MB is closed, the relay AB may function to open the switch AB2 without afiecting the relay MB.

The operation of relay MB, as stated, closed switch MR3. This switch is connected through a conductor 852 with conductor is? and is further connected through conductor 8l3 with solenoid 888. Solenoid 888 is connected through a conductor MA with the bus 196. Closure of switch M133 energizes solenoid 888 which opens the valve I83 controlling the oil pressure system and sets the governor 159 into operation and starts the operation of the turbine or prime mover driving generator '55 i.

For operating certain of the equipment controlling generator 151, two single phase transformers EH5 and 816 are employed having primarics 8|! and 8H8 and secondaries 8l9 and 820. The primaries. 8!? and Bill of these transformers are connected to the generator line GLB and receive potential from the generator when the same comes up to speed. The two secondaries SH! and 828 are connected together and are connected to a common lead 82! which in turn is connected to the common lead previously referred to. The secondary 820 of the transformer M6 is connected toa bus 822 and the secondary 8!!) of transformer M5 is connected to a bus 812, which provides potential for operating a number of devices to be presently referred to.

The switch MB4 of relay MB is connected through a conductor 823 with bus 822 of transformer M6 and is further connected through a conductor 824 with the normally closed switch CBBT of circuit breaker CBB. This switch in turn is connected through conductor 825 with the centrifugal switch 160 of governor 159. A conductor 826 leads from this switch to the normally closed switch XA9 of the transfer relay XA for generator 150. This switch is connected through a conductor 821 with coil XBI of relay KB. A conductor 828 connects this coil with the common bus I15. When the generator gets up to speed, switch 760 closes which completes the circuit through the various switches and conductors last named providing the exciter is in operation and is delivering sufiicient excitation current to bring the generator up to voltage. When this occurs,

the coil XBI of relay X5 is energized which in of the generators at the same time which Q could not be accomplished unless all of the transfer relays of the other generators are out. When coil XBI is energized relay X3 is closed and further new circuits established, which operates the speed matching and synchronizing mechanism of the invention which will'now be described in detail.

The speed matching mechanism of the invention comprises two motors 832 and 833 which are preferably in the nature of synchronous motors or motors rotating at a speed proportionate to the frequencies of the systems from which they are operated. Motor 832 is operated from the generator to be cut in while the motor 833 is operated from the distribution system. The motor 832 drives a governor 834 adapted to swing a lever 835 and to slide a contactor bar 838 in a direction parallel to the axis of the motor shaft. Motor 833 similarly drives a governor 831 which is connected to a swinging lever 838 and is adapted to move a contact bar 839 in accordance with the speed of said motor. The governors 834 and 831 are so constructed that both contactor bar 836 and contact bar 839 move in the same direction as the two motors increase in speed so that relative movement of the contactor bar 836 and the contact bar 839 is only produced when the motors travel at different speeds and the relative position of said contact bar and contactor bar are independent of the direction of rotation of the motors, the absolute speed of the motors and the phase relation of the currents energizing the same. The contactor bar 838 is provided with two contact fingers or contactors 840 and 84I while the contact bar 839 is provided with three contacts 842, 843,844. The former is adapted to contact with contactor 848 while the contactor 84! is adapted to alternately en gage with either contacts 883 or 8 which are insulated from one another and from the contact 842.

The synchronizer used in conjunction with the invention may be of any ordinary form and as stated is indicated in its entirety at 845. This synchronizer may be provided'with separate rotor and stator coils (not shown) which are connected together and to a common binding post 845. These two coils are further connected to two other binding posts 841 and 848. The synchronizer 845 is constructed with a shaft 849 adapted to be rotated through when current energizes the coils of said synchronizer. This shaft rotates at a speed dependent upon the difference in frequencies of the currents in the two'lines connected to the synchronizer. Said synchronizer is further constructed so that the shaft 849 has a definite position with respect to the synchronizer case when the currents in the two lines energizing the synchronizer are in phase relation. Connected to the shaft 849 are two discs 850 and 85! of insulating material. The disc 858 is provided with a, contact 852 which is connected to the shaft 838 while the disc 85! is provided with a contact 853, also connected to shaft 843 and with two other spaced contacts 354 and 855 disposed on the side of the disc 85! opposite to the contact 853. These contacts, are connected to two other contacts 857 and 858 which are adapted to be alternately engaged by a finger 859 frictionally driven by shaft 839 and adapted to contact with either of the contacts 85? and 858 depending upon the direction of rotation of said shaft and to so remain throughout the continued rotation of the shaft. Two contact rollers 868 and 88l diametrally opposite are adapted to engage the disc 858 and alternately contact with contact 852. Two similar rollers 862 and 883 are diametrally positioned and correspond with rollers 868 and 86! and are adapted to alternately engage the respective contact 853 and the contacts 854 or 855.

Operating in conjunction with the speed matching and synchronizing mechanism a control relay S is employed which comprises a coil Si and two normally open switches S2 and S3. In addition to this relay, a safety relay SE and an auxiliary relay SF are employed for operating the circuit breaker CBB. The relay SE comprises a coil SE! and two normally open switches SE2 and SE3. The relay SF comprises a coil SFi, two normally open switches SF2 and SP3 and a timing device SP4 which retards the closing of relay SF and allows it to open instantly.

The various parts of the synchronizing and speed matching mechanism are connected together as will now be described. Current for operating the two motors 832 and 833 and for operating the synchronizer 8&5 is procured by means of the transfer relay XB through the following circuits. The bus ill from transformer E89 is connected through a conductor 884 with switch XB5 of relay KB. This switch is in turn connected through conductor 885 with another bus 866. Bus 868 is directly connected to one of the terminals 83'! of motor 832. The common terminal of this motor is connected to another bus 883. This bus is connected through a conductor 8% with switch X132 which in turn is connected through a conductor 814 with the bus H6 which as previously explained is connected to the transformer W8. It will hence be readily comprehended that when the two switches XBE and X32 are closed three-phase current is provided for operating motor 832.

Motor 833 as previously stated is operated from the potential of the generator line GLB. Transformers M5 and BIG are utilized for this purpose. The bus 872 is connected to the secondary 8!!! of transformer 8R5 and also to switch 2533.

Switch X33 is connected through conductor 813 with a bus 8l4 which in turn is connected to the terminal 815 of motor 833. The common terminal of this motor is connected through a conductor 816 with the common bus 115. The other terminal of this motor is connected through a conductor 811 with a bus 83!. This bus is connected through a conductor 83!] with switch XB4. Switch 'XB4 is connected through conductor 829 with bus 824 which in turn is connected through switch MB4 with conductor 822, the latter conductor leading from the secondary of the transformer 8H5. When switch X134 and switch X133 are closed motor 833 is provided with current from the generator line operating said motor at a speed corresponding with the frequency of the potential in the generator line.

The motor 8H) for controlling the governor 759 is operated through contactor 84! and the two contacts 843 and 844. In conjunction with these two contacts two centrifugal switches 819 and 888 are employed which are adapted to be operated by the governors 834 and 837 and which become closed when the two motors 832 and 833 reach substantially synchronous speed. The motor are is preferably provided with two windings connected together through a common conductor 88! with the common bus H5. The other two terminals of motor 8H3 are connected through two conductors 882 and 883 with the two switches X33 and XBl. These switches are in turn connected through conductors 884 and 885 with two busses 886 and 88'! directly connected to contacts 843 and 844. Both the contact fingers 840 and 8M are connected to a conductor 888 which in turn is connected to switch 819. Switch 819 is connected through a conductor 893 with switch 888 whichin turn is connected through a conductor 894 with bus 8'14 previously referred to.

When the contactor 84! engages one of the contacts 843 or 844 a circuit is completed through motor 8&8 which causes said motor to rotate in a particular direction depending upon which one of the contacts 843 or 844 is closed. Assuming contactor 84H to be contacting with a contact 843, the following circuit would be closed. Commencing at the common H5, current would then flow through conductor 88l, motor 8H1, conductor 882, switch 238, conductor 884, bus 8855, contact 843, contactor 84E, conductor 888, switch 819, conductor 893, switch 888, conductor 894 and to the bus 814. From this bus, current would flow through conductor 8T3, switch X33, conductor 812, and back to the transformer 8| 5. When the contactor 84l contacts with contact 844, a similar circuit is completed through the other winding of motor 8E0 which causes said motor to operate in the opposite direction. As the two motors 832 and 833 operate, variations in the speed thereof caused by difference in the frequencies of the generator to be cut in and the distribution system cause the relative movement of the contactor 84! with respect to the contacts 843 and 844 which in turn operates motor 8H to re-adjust the governor and cause the generator to rotate at the proper speed.

When the generator produces voltage of the proper frequency, contactor 84! is just in between the two contacts 843 and844 and contactor 848 is in contact with contact 842. Contact 842 is connected through a conductor 895 with the coil SI of relay S which in turn is directly connected to the common bus H5. The two switches S2 and S3 of this relay control the current for energizing the synchronizer 845. The switch S3 is connected through a conductor 89'! with bus 866 which as previously explained is energizedfrom transformer 169. The switch S2 is connected through a conductor 898 with bus 83! which as previously explained is energized from transformer 8l8. The switch S3 is further connected through a conductor 899 with the binding post 848 of synchronizer 845 while the switch S2 is connected through a conductor 998 with the other binding post 841 of said synchronizer. The common binding post 848 of the synchronizer is connected through a conductor 98! with the common bus 115. As soon as relay S! is closed the synchronizer 845 is energized and commences to rotate.

The relays SE and SE are connected to the other parts of the synchronizing apparatus as follows. A conductor 982 connects the roller 858 with switch SE2 and also with coil SE! which latter is directly connected to the bus 115. Another conductor 998 is connected to switch S2 and also to switch SE2. Switch SE3 is connected through a conductor 989 with roller 86! and through another conductor 985 with both the switch SE2 and the coil SF! of relay SE. Coil SEl of this relay is directly connected to the common bus 115. Switch SE2 of relay SE is connected through a conductor 986 with roller 882. Switch SE8 of this relay is connected through 'a conductor 881 with roller 883 and to a bus 988.

which operates the circuit breaker in a manner to be presently described. The shaft 849 of synchronizer 845 is connected through a conductor 9! with conductor 988 previously referred to.

In the connection of the generator to the system, it is necessary that the relay SE first close before the circuit breaker can be connected. The circuit through the coil SE! of this relay is broken through switch SE8. It hence becomes necessary that relay SE which is a safety relay be operated before the generator can be synchronized with the system. Roller 858 is in the circuit through the coil SE! of relay SE. A circuit is completed through this coil when the shaft 849 has rotated sufiiciently to bring the contact 852 of disc 858 in contact with roller 85!). When this occurs, the following circuit may be traced. Commencing with bus 835 which, as previously stated, was connected to transformer 8I8, current flows through current conductor 898, through switch S2, which was closed upon contactor 848 contacting with contact 842, through conductor 998, conductor 9! shaft 849, contact 852, roller 86!), conductor 982, coil SE! and back to the common bus 115. This operates relay SE closing switches SE2 and SE8. Relay SE is maintained through the switch SE2. The circuit for maintaining this switch also commences at bus 83! and includes conductor 898, switch S2, conductor 983, switch SE2, conductor 982, coil SE! and the common bus 125. Relay SE is now maintained closed and the operation of this relay completes another circuit through switch SE3. Commencing with shaft 848 of relay 885 which as previously explained is connected to transformer 8E8 current flows through contact 852, roller 85!, conductor 984, switch SE8, conductor 995, coil SEE of relay SF and back to the common bus H5. This energizes relay SE which closes switches SE2 and SE3. Switch SE2 is a maintaining switch for relay SE. Bue to the position of contact 858 and contact 852 roller 882 is in engagement with contact 853 when roller 85! is in contact with contact 852. Current then flows from shaft 849 through contact roller 852, conductor 986, switch SE2, conductor 995, and through coil SF! of relay SF back to the common bus 115. This maintains the circuit through relay SF maintaining switch SE3 closed. Closing of relay- SE is retarded through the device SE4. If the duration of contact through roller 88! and contact 852 is sufficient, switch SE3 is finally closed and the circuit breaker operated.

The two contacts 854 and 855 are placed on the disc 85! in such positions that the same are in advance of the roller 853 when the disc 85! is so disposed that the current in the distribution system from the generator have the same phase relation. It hence becomes evident that the roller 883 engages these contacts slightly beforethe two currents are in phase. This is for the purpose of compensating for the time required by the circuit breaker to close, particularly where slow acting circuit breakers are employed. Under proper conditions, current flows from the shaft 849 through finger 859 through either of the contacts 851 or 858 as the case may be and the corresponding contacts 854 and 855 connected therewith through roller 883, conductor 981, switch SE3, and bus 988 to the apparatus for operating the circuit breaker which will be presently described in detail. The reason for the use of the finger 859 and the two contacts 851 and 858 is to prevent the unintended closing of the circuit breaker in the event the same is not closed when the roller 883 passes over the first contact. In such case the speed of the disc 85! might be such as to cause closing at such latter contact, circuit being broken in the second contact through finger 859.

For the purpose of operating the circuit breaker CB an auxiliary relay SH is employed. This relay comprises a coil SH! and a normally open switch SHE. This relay is further timed through a dash pot SH3 to cause the switch SH2 to quickly close and to remain closed for a predetermined length of time after the deenergization of coil SHI. The coil SH! is connected through a conductor 9!2 with the common bus 115 and through another conductor 9 !3 with switch X88. Switch X288 is connected through a conductor 9) with bus 988 previously referred to. The switch SH2 is connected through a conductor 9M with the coil CBB! of circuit breaker CBB which coil is further connected through two conductors 9!5 and 9! 8 with the common bus 115. The other side of the switch SH2 is connected through a conductor 9!1 with conductor 824, which as previously described was connected to conductor 829 and to switch MB4 of relay MB.

When switch SP3 is closed and roller 863 is in contact with one of the contacts 854 or 855 the following circuit is established. Commencing with the bus 822 connected to transformer 8l6 current flows through conductor 823, in B4, 824, conductor 829, switch S2, conductor 988, conductor 9! I, shaft 849, contact finger 859, contact. 851 or 858, corresponding contacts 855 or 854, roller 883, conductor 981, switch SE3, bus 988, conductor 9H8, switch XB8, conductor 9!3, coil SHI, conductor M2, and back to the common bus 115. This operates the relay SH. Another circuit is then completed through the switch SHZ of said relay. Commencing with the common bus 135, current flows through conductor 9l6, conductor 8! 5, coil CBBl, conductor 9 !4, switch SH2, conductor 9H, conductor 828, switch MB4, and bus 822 back to the transformer 8l6. This energizes the circuit breaker CBB closing the various switches thereof and connecting the generator line GLB to the distribution line DL. At the same time, switches CBB5 and CBB6 are closed and switch CBBl opened. The relay SH is maintained closed through the contact 853 on disc 85! and the roller 862. Due to the peripheral extent of the contact 853 the circuit is maintained closed through this contact and the roller 862 a sufficient length of time to cause the closure of the circuit breaker CBB which is held latched through the latch lug LBZ of solenoid LB to be presently described in detail.

For maintaining circuit breaker CBB closed, a latch solenoid LB is employed having a coil LBI. This solenoid is provided with a latch LB2 which is adapted to engage a latch lug LE3 on the circuit breaker and to magnetically hold the said circuit breaker closed when once the same has been actuated. The latch member LBZ remains in latched position once the same has been latched until it is tripped through the operation of the coil LBl thereof.

As soon as circuit breaker 033 goes in, the normally closed switch CBBl of the circuit breaker is open. This opens the circuit through the coil XBI of transfer relay XZB deenergizing this relay and disconnecting the synchronizing apparatus from the generator 715i and associated circuits thereof. The synchronizing apparatus is now available for use for synchronizing the other generator 1750, or in the case more than two generators are employed, one of the other generators.

For the purpose of regulating the voltage system, the voltage regulator l8! is employed which is provided with a direct current coil 932i, and an alternating current coil 922. These coils actuate either or both of two vibrators Q23 and 924 which operate in conjunction with fixed contacts 925. The vibrator 923 serves to regulate the voltage of the exciter lfil while the vibrator 924 serves to regulate the voltage of the exciter N52. The AC coil 922 is connected through a conductor 525 with the common bus H5 while said coil-is further connected through a conductor 926 with the bus 'll'l leading from transformer l69. The coil 92H is connected to two busses 927 and 928 which may receive potential from either of the exciters ltl or 1162. For connecting the potential regulator to the exciter 162 a relay ED is employed which comprises a coil EDi, four normally open switches EDZ, ED3, ED and ED5 and one normally closed switch EDE. The coil EDl of this relay is connected through a conductor 929 with a common bus W5 and through a conductor @343 with conductor 92E) previously referred to which is closed through the circuit breaker CBB. When the circuit breaker CBB is operated, a circuit is established which energizes the coil EDI from transformer 8l6, operating relay ED.

Operating in conjunction with the voltage regulator is a rheostat 935 which is connected through a conductor 932 with the rheostat E92 and with the conductor F93. This rheostat is further connected through a conductor $333 with the shunt coil lb? of the exciter F62. The rheostat 93l may be shunted through the switch EDii of the relay ED and through a switch EG2 of a relay EG having a coil EGi. The coil of this relay is connected through a conductor 934 with the conductor E93 from the armature E65 of eXciter I62 and through another conductor 935 with the series coil ice of the exciter 5&2 so as to receive potential directly from the exciter. When the exciter voltage builds up sufficiently the switch EGZ which is a normally closed switch is opened and the circuit therethrough broken. This switch is connected through a conductor 936 with the conductor F93 and is further connected through a conductor 93'? with switch EDt. Switch EDS is connected through a conductor 938 with switch ED5 and also through a conductor 943 with conductor 933 leading from rheostat 93L Both switches EDS and EG2 are normally closed switches so that in the initial operation of the exciter 1752 the rheostat 936 is shunted and full potential is had on the field coil I56 of the generator until the generator and exciter get up to speed and the exciter delivers sufiicient voltage to operate coil EGl. When this occurs, the circuit shunting the rheostat 533i is broken and the rheostat 93! may thereafter control the voltage regulator to maintain the proper voltage at the exciter and the corresponding voltage in the distribution line. When the voltage regulator is finally connected. which occurs when relay ED is operated, switch. EDii is also opened causing the further opening of the circuit shorting the rheostat 93!.

The rheostat 953i is adapted to be shorted through the vibrator 924 of the voltage regulator l3l through the following circuit. This circuit comprises a conductor see which is connected to conductor E93 and indirectly to the rheostat 93!. Said conductor is further con.- nected to switch ED i of relay ED. Switch ED& is connected to a conductor 949 which in turn is connected to bus 921. A conductor 9M leads: from the bus $32l to the fixed contacts 925 of the voltage regulator. Vibrator 92! is connected.

through conductor 9&2 to switch ED5 which in:

turn is connected through the conductor 943 with the other side of the rheostat 93!. By means of this circuit, it can readily be comprehended that when the relay ED is actuated and switches EDA and ED5 closed that the vibrator 924 may function to short out the resistance of the rheostat 935 in a manner to control the voltage of the exciter 162 as is now well understood in the art.

Current for operating the direct current coil 92 l is procured through the bus 928 and through the bus 92'! previously referred to. A conductor 9 35 is connected to the switch ED2 and also to the bus 928. Switch EDZ is further connected through a conductor 9 36 with the series coil 168 r of eXciter 762. When the relay ED is closed, current is had through the switches EDZ and ED? from the exciter l62 which energizes the buses 92?! and 928 and provides current for the distant current coil 92l of the voltage regulator.

In the normal shut down of the generator the following procedure is adopted: Switch E98 at the control station is first opened which de-energizes master relay MB. This opens switch M133 which controls the current through the starting solenoid 808. Deenergization of this solenoid causes the governor to close the gate and reduce the speed of the prime mover. As the gate closes the generator reduces speed until finally the generator comes to rest. The deenergization of relay MB at the same time disconnects the various circuits associated with the generator so that when the generator finally comes to rest, the entire apparatus associated therewith is completely disconnected lrom the distribution system.

The speed matching apparatus, the synchronizing apparatus and the voltage regulating apparatus may also be used in conjunction with the generator F59 for automatically connecting the same to the line and forcontrolling the voltage of the distribution system.

For providing potential for operating the various apparatus used in conjunction with the control and operation of the generator I50, two transformers 981 and 988 are employed which are provided with primaries 989 and 990 and with secondaries 99I and 992. The primaries 989 and 990 are connected together and to phase 2 of the generator line GLA through a conductor 993. These primaries are further connected through conductors 994 and 995 with the phases 3 and I of the generator line GLA. The secondaries 99I and 992 of these transformers are connected together through a conductor 996 which in turn is connected to the common bus 115. The secondary 992 is connected to a bus 99! which serves to feed certain of th apparatus used while the secondary 99I is connected to a conductor 999 which will be again referred to.

The master relay MA- for generator I59 similar to the master relay MB is operated from the control line H8 and I19. This relay is connected in much the same manner as the relay MB having, however, an additional switch MAG. The switch 299 in the control station is used to control the operation of relay MA. This switch is connected to the side 119- of the control line and is connected through a conductor I998 to both of the switches AA2 and AA3 oi the relay AA and also to all three of the switches MA3, MA2, and MAG of master relay'MA. Switch AA2 is connected to switch MAZ through a conductor I9 I 5 which shunts the switch MA2. Switch MAZ is further connected through a conductor I999 to a normally closed switch ECG of the exciter relay EC which in turn is connected through a conductor IUI I with coil MAI of relay MA. This coil is in turn connected through a conductor I0 I 2 with bus I99 leading from the side I78 of the control line. The conductor I999 connected with switch MA2 is further connected through a conductor IIlI5 with the normally closed switch AA2 of anti-start relay AA. This switch in turn is connected to the conductor I699 leading from switch 290. When switch 299 is closed a circuit is established through the coil MAI which energizes relay MA and closes the various normally open switches thereof. This circuit may be traced as follows. Commencing with bus I99 from the side N8 of the control line, current flows through conductor IIlIZ, coil MAI of relay MA, conductor II] I I, normally closed switch ECB, conductor I099, conductor IIJI5, switch AA2, conductor I998, back to the other side 519 of the control circuit through the switch 299. This energizes coil MAI and operates relay MA. Operation of relay MA closes switch MA5 which completes a circuit through the coil AAI of anti-start relay AA. This circuit includes a conductor I913 which. is connected to said switch and to the coil AAI of relay AA'. This coil is further connected. through a conductor I9 I 4 to the bus I96. When the switch MAS is closed the-following circuit is completed.

Starting with bus I96, current flows through conductor IBM, coil AAI, conductor IBIS, switch MAS, conductor I098 and through switch 299 back to the other side I19 of the control line; The energizing of coil AAI of relay AA closes switch AA3 and at the same time opens switch AA2. The circuit for energizing coil MAI included switch AAZ and said circuit would have been opened excepting for the switch MAL on relay MA which is in parallel with theswitch AA2 and which maintains the energizing circuit for said relay.

The relay AA is maintained operated through the switch AA3 thereof. This switch is connected through the conductor I9I3 with coil AAI. When switch AA3 is closed the following circuit may be traced. This circuit includes conductor I998, switch AA3, conductor I9l3, coil AAI, conductor IIJI I, which conductors I098 and HEM are fed from the control circuit 113 through the switch 299. Belay AA is now maintained until the switch ZDB-ismanualIy opened so that in case the system is shut down through failure, the same cannot be reconnected unless the operator manually operates switch 209.

Theclosing of the master relay MA closes switch MA3 wl1ich sets the governor I51 into operation. This switch is connected to the conductor I099 which, as previously brought out, is connected to side I19 of the control line through switch 299. Switch MA3 is further connected through a conductor I9 I? with solenoid 895 which in turn is connected through a conductor IOI8 with bus I96 leading from the side IIB of the control line. eratesthe governor I57 which opens the gate controlling the flow of water to the turbine and sets the generator I59 into operation.

The armature 962 of the exciter I6! is connected to a rotating part of the generator I50 so that said exciter is brought up to speed as the generator comes .up to speed. The exciter I6I is connected through various circuits to excite the field coil I53 of generator I59 as will be presently described in' detail, which causes the generator I59 to deliver potential to the generator line GLA. This provides potential. at the transformers 99Iand 988 which furnish current for operating certain of the equipment used in conjunction with the generator I59. After the governor I51 gets up tospeed, the centrifugally operated switch I58 is closed which, as will be presently explained, functions to set in operation the various synchronizing. and speed matching apparatus in conjunction with generator I59.

For the purpose of connecting the generator to'the speed matching and synchronizing apparatus, the switch XA previously referred to is employed. This switch is connected to the various busses and conductors from the speed ductor 986'with the secondary 99I of transformer 98?. Switch XA4 is connected through a corn ductor998 with switch MA4 of master relay MA. Switch MAE and MA I are connected through a conductor 999 with bus 99I leading from transformer 988. Switch XA5 is connected through a conductor I909 with bus H1. The two switches XA6 and XAI are connected through conductors HIM and I992 to the two windings of the motor 8910f the governor I51, the common connection of the windings of this motor being connected 1 through-a conductor I993 with the common bus I15. Coil XAI of relay XA is connected to the common H5 through a conductor I094 and is further connected through a conductor I995 with the switch X39 of relay KB. This switch is in Energization of this solenoid opturn connected through a conductor I066 with the centrifugally operated governor switch I58 which in this case is connected through a conductor lillii to a normally closed switch LA2 of the latch relay LA for the circuit breaker CBA. Conductor will connects this switch with the conductor 988 previously referred to, which as stated was connected to switch MA4 of master relay MA. When the master relay MA is closed, a circuit is completed from bus 99'! leading from transformer 5538 through conductor 999, switch MA4, conductor 998, conductor man, switch LA2, conductor Milli, switch "E58, conductor I886, switch X39, conductor i685, coil XA! of relay XA, conductor wilt, back to the common bus 115. This energizes relay XA closing the various switches thereof and connecting the generator system to the speed matching and synchronizing apparatus in identically the same manner as relay XB. The speed matching then commences and motor 801 is energized to rotate in either direction to vary the speed of the generator so as to bring the current in the generator line in synchronism with the current in the distribution line. Inasmuch as the operation of the speed matching and synchronizing of the generator i5!) is identically the same as with the generator "55!, the operation of the same will not be repeated. When, however, the generator is in synchronism, an auxiliary relay SG is energized which serves to close the circuit breaker CBA. This relay comprises a coil SGi and a normally open switch SGZ. The coil SGi is connected through a conductor HHS with the common bus H5, and is connected through another conductor i020 with switch XA8 of relay XA. When relay XA is closed, current flows from transformer 988 through bus 99?, conductort ilfi, switch MA i of master relay MA, conductor 998, switch XA4, bus 33!, conductor 898, switch S2 of the synchronizing relay which is closed'after synchronizing commences, conductor 953i), conductor 9i i, shaft 8 39, contact 854 or 855, roller 863, conductor 901, switch SF3, conductor 9M3, conductor 985, switch XAB, conductor itZil, coil SG! and conductor new back to' the common bus H5. This operates relay SG. The switch SGZ of relay SG is connected through a conductor iGZl with coil CBA! of circuit breaker CBA which in turn is connected through conductor i922 with the common bus H5. The other side of switch SGZ is connected through a conductor H323 with conductor 998 which is connected to the transformer 988 through switch MA l and conductors 99S and 99?. Closure of switch SGZ energizes coil CBAI which closes the circuit breaker and connects the generator to the line.

The latch relay LA comprises a coil LAi, and a normally closed switch LA2, previously referred to. When the relay is in normal position it is disengaged from the circuit breaker. When energized, it opens switch LA2 and engages a suitable latch member on said circuit breaker holding it in closed position. Inasmuch as the relay XA is energized through a circuit including switch LA2 on the latch relay LA, relay XA will be opened when the latch relay is energized. This relay is energized through a circuit including the switch CBAEi on the circuit breaker. It must hence become evident that relay SG must be maintained long enough to cause the circuit breaker to close since the said relay is maintained from relay XA which in turn is indirectly dependent on the circuit breaker for current. The coil LA! of the latch relayLA is connected through a conductor I026 with switch CBA6 of the circuit breaker CBA. This switch is further connected through a conductor i027 with the conductor 1'84 from the eXciter ifil. The other side of the coil LAI of relay LA is connected through a con- 5 ductor H329 with the conductor 'l8'i from exciter 15L Thus, current normally flows through the latch relay coil LAi which holds the circuit breaker CBA closed.

When the generator 550 is connected to the 10 distribution line DL, the exciter Til thereof is connected in parallel with the exciter 762 to the potential regulator E85. This is accomplished through the relay EC which is similar to the relay ED. This relay comprises a coil ECi, four normally open switches ECZ and EC3, E04 and EC5, and a normally closed switch ECG. Operating in conjunction with the relay EC is another relay EF comprising a coil EFl a normally closed switch EFZ, and a normally open switch EFS. The coil ECI of relay EC is connected through a conductor l03l with the common bus H5, and is connected through another conductor i632 with the switch CBA5 of the circuit breaker CBA. This switch is in turn connected through a conductor N33 with conductor l 623 which in turn is connected to conductor 938, said latter conductor, as previously brought out, being connected through the master relay with the transformer 983. When the circuit breaker CBA closes, switch CBA5 closes and current is established through the coil ECl of relay EC operating said relay and closing the various normally open switches thereof. The switches EC2, E03 and E04 are connected through conductors I834, I035, and I836 with the current coil and the two brushes of the armature of the exciter lei in the same manner as relay ED. The two switches E02 and EC4 are connected to the conductors 928 and 552 the same as switches EDZ and ED4 of relay ED. The two switches EC3 and ED3 are both connected together through a conductor H335. The switch E05 of relay EC is connected through a conductor 1 836 with a second rheostat I031 which in turn is connected to the conductor i8? and the rheostat (86. Switch EC5 is further connected through a conductor N38 with the vibrator $23 of the potential regulator 78!. When the coil ECl is closed, the two exciters lfii and 762 are connected to-- gether in parallel, and to the voltage regulator it]. This regulator functions as previously described to regulate the voltage of the distribution system and the two exciters.

To cause the generator iiii to build up rapidly the rheostat i037 is shunted during the initial operation of the exciter. This is accomplished through relay EF. The coil EFl of this relay is connected through a conductor i039 with the conductor l8! leading from the armature 952 of said exciter. The other side of this coil is con- 60 nected through another conductor I943 with the conductor I034 leading to the series field coil 163 of said exciter. When the exciter voltage builds up sufficiently the coil EFI is energized and the relay EF operated. The switch EF2 of this relay 65 is connected through a conductor [Ml with one side of the rheostat we": and through the conductor I036 previously referred to to the other side of said rheostat. Switch EFZ being a normally closed switch normally shunts the rheostat new 70 giving the exciter maximum voltage before starting. When this switch opens, the rheostat N38! is cut into bring the voltage to normal prior to the connection of the generator to the system.

Relays EC and EF form a protective device for 75 opening the master relay MA in the event that the exciter i! drops below a predetermined value. The master relay coil MA! is included in a circuit containing switches E05 and EF3 in parallel. Switches E06 and EF3 are connected together through two conductors 96 and 9?. Switch ECii serves to close the control circuit prior to the closing of the circuit breaker. Switch EF3 is a protective switch which is adapted to open the control circuit in case the exciter voltage drops to a predetermined value. Normally this switch is open. However, switch ECE is normally closed and the circuit completed through it. When the exciter voltage builds up, relay EF is operated and switch EF3 is closed, paralleling switch E06. Thereafter when the shunt circuit through switch ECS is opened which occurs when the exciter is connected to the busses $28, 927 and I835, the control circuit is maintained closed through said switch EF3. After such opening of switch ECB, further opening of switch EF3 through drop in potential of the exciter will open the control circuit and shut down the system.

In order to reduce the load on the generator in case the generator overspeeds, relay NA is employed. The relay NA includes coil NAE, two normally closed switches NA2 and NAB and a normally open switch NA4. In addition to this relay, a mercury switch M162 is employed which is mounted upon the generator and which is adapted to close when the generator rotates at a predetermin d speed. In order to simplify the connections of this switch to the system, the common bus H5 is grounded and likewise one side of the switch 362 is grounded. The other side of this switch is connected through a suitable slip ring or equivalent device and through a conductor H353 with the switch NA3 of relay NA. This switch is connected to the switch NA4 and also to the coil NA! of said relay through conductor i564, said coil being directly connected to a conductor H353, leading from conductor 332. When switch H362 is closed, current flows from the ground through said switch, through conductor 1063, switch NA3, conductor i864, coil NAI, conductor i653 and conductor I632, which as previously described, is connected to the transformer 938 through the circuit breaker switch CBA5 and through the master relay switch MAA. Closure of this circuit energizes coil NA! of relay NA which operates said relay. The relay NA is of such design that the switch NA l is closed and both switches NA3 and NA2 opened upon said relay being initially energized through the switch NA3 so that once the said relay is started the same continues to operate until switch NA4 is closed and the switch NA3 opened. Closure of switch NA4 controls another circuit. This switch is connected through a conductor i655 with the common bus H5. The actuation of relay NA opens switch NA2 which deenergizes the load pick up solenoid 8% taking 01f the load and causing the generator to slow down.

, For the purpose of causing the generator 16| to take on load the solenoid 806 previously referred to, is employed. This solenoid is connected through a conductor 35! with the common bus N5 of the system. The said solenoid is further connected through a conductor 1552 with a normally closed contact NAZ of the relay NA to be subsequently referred to. The switch NA2 is connected through a conductor H353 with the conductor i932 previously referred to. The circuit through solenoid 895 is controlled through the switch CBA5 of the circuit breaker CBA and may be traced as follows: Commencing with the transformer 992, current flows through conductor 99! through conductor 999 through switch MAG of the master relay MA which of course is closed throughout the operation of the system, through conductor 998, through conductor I023, through conductor I033, through switch CBA5, which has been closed upon the operation of the circuit breaker, through conductor I032, through conductor H353, through switch NA2, through conductor I052, through the solenoid 806 and through the conductor I05! back to the common bus 175. Actuation of this solenoid controls the action of the governor causing the gate to open and the generator totake on load.

The advantages of my invention are manifest. The system is fully automatic in all respects. The system may be remotely controlled and operated to perform all of the functions of a manually controlled system. The system is extremely flexible and adaptable to varying conditions of load and water supply. Protective devices are embodied which prevent injury to the machinery and to the system. The system is practically fool proof and employs only such equipment as will not readily get out of order.

Changes in the specific form of my invention as herein disclosed may be made within the scope of What is claimed, without departing from the spirit of my invention.

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In combination with a distribution system and a plurality of generators adapted to be connected thereto and each having an exciter, an exciter bus, circuit breakers for connecting said generators to the distribution system and means operated by each of said circuit breakers for connecting the corresponding exciter to said exciter bus upon connection of its generator to the distribution system.

2. The combination with a power line, a plurality of generators and a remote selecting apparatus for determining the connection of a selected generator to the power line, of a single control apparatus, transfer relays for each generator for connecting the generator to the control apparatus, main switching means for each generator for connecting the generator to the power line, means for connecting said remote apparatus to said transfer relays extending through contacts of the main switching means which are closed when said main switching means is in position for disconnecting the generator and power line, energizing circuits for said control apparatus extending through said transfer relays, and actuating circuits for said main switching means under the control of said transfer relays and control apparatus and whereby the remote apparatus may actuate the selected transfer relay and thereby produce a coupling of said control apparatus with the corresponding generator and a closing of said corresponding main switching means from said control apparatus, and whereby the main switching means in closing accomplishes a reverse actuation of the transfer relay and thereby uncouples said control apparatus from the corresponding generator.

3. The combination with a power line, a plurality of generators and a remote selecting apparatus for determining the connection of a selected generator to the power line, of a single control apparatus, transfer relays for each generator for connecting the generator to the control apparatus, main switching means for each generator for connecting the generator to the power line, means for connecting said remote apparatus to said transfer relays extending through contacts of the main switching means which are close-d when said main switchingmeans is in position for disconnecting the generator and power line, said connecting means for each transfer relay extending through contacts in all other transfer relays which are closed when the other transfer relays are in unactuated condition and are open when the corresponding transfer relay has been actuate-d, energizing circuits for said control apparatus extending through said transfer relays, and actuating circuits for said main switching means under the control of said transfer relays and control apparatus and whereby the remote apparatus may actuate the selected transfer relay and thereby produce a coupling of said control apparatus with the corresponding generator and a closing of said corresponding main switching means from said control apparatus, and whereby the main switching means in closing accomplishes a reverse actuation of the transfer relay and thereby uncouples said control apparatus from the corresponding generator.

4. The combination with a distributing system and a plurality of generators adapted to be connected thereto and each having an exciter, an exciter bus, circuit breakers for connecting said generators to the distributing system, resistances in series with the field coils of said eXciters, switches for shunting said resistances, means responsive to the exciter Voltage for opening the switch corresponding to the eXciter when the exciter voltage reaches a predetermined value, and means for connecting each exciter to the exciter bus upon connection of the corresponding generator to the distribution system.

5. The combination with a distributing system and a generator adapted to be connected to said system, of main switching means for connecting the generator to said system, a synchronizer operated by the generator and sysmm for controlling the closing of said main switching means, actuating means for closing the main switching means and including an actuating circuit, a normally open switch in said circuit, means controlled by said synchronizer for closing said switch rapidly, a time delay device for maintaining said switch closed for a predetermined length of time, means for restoring said switch to its normally open position at the expiration of said time, whereby said actuating circuit is closed at said switch for said predetermined length of time, and a further switch controlled by the synchronizer for completing the closing of said actuating circuit at a time interval after the closure of said normally open switch varying inversely with the frequency difference of the generator and system.

6. The combination with a distribution system and a generator adapted to be connected thereto and having an exciter, of main switching means for connecting said generator to the system, an exciter field rheostat, a control relay including contact means connected in shunt of at least a part of said field rheostat, circuit means responsive to the eXciter voltage for opening the contact means at a predetermined exciter voltage, said contact means operating when closed to ensure a quick pick-up of the eXciter, said circuit means being connected to said control relay, further contacts controlled by said relay and closed thereby at a predetermined eXciter voltage, means for holding said main switching means closed, auxiliary contacts closed when the main switching means is closed, and further circuit means connecting said further and auxiliary contacts and operative to energize said holding means from said exciter after the main switching means has been closed.

7. The combination with a distribution system and a generator plant, of main switching means for connecting said generator to the system, a master relay, means controllable from a remote point for energizing said master relay and including a circuit, a second relay having normally closed contacts, a safety switch closed from the generator when the latter is in condition for starting, a further circuit including said contacts and switch for actuating said master relay, generator synchronizing means and circuits therefor, said synchronizing circuits being closed upon energization of said master relay, means controlled by the said synchronizing means for closing said main switching means through said master relay, a second normally open safety switch connected for closing when the generator plant is not in condition for connection to the system, and a circuit including said second safety switch for actuating said second relay to open the contacts thereof and deenergize said master relay and thereby prevent closing of said main switching means.

8. The combination with a distribution system, of a plurality of generators and a remote selecting apparatus for determining the connection of a selected generator to the system, of a single synchronizing means capable of bringing any said generator into synchronism with the system and including circuits suppliable from the system and the selected generator, selecting relay means controlled by said remote apparatus for connecting said synchronizing means to a selected generator for synchronizing the same, main switching means for each generator for connecting the generator to the system, means actuated through said synchronizing means for closing the main switching means of the selected generator when the associated generator is at a predetermined condition of synchronism with respect to the system, and means independent of the synchronizing means for maintaining said main switching means closed when the selecting relay means has been operated to disconnect the synchronizing means from said corresponding generator.

9. The combination with a distribution system, a plurality of generators and a remote selecting apparatus for determining the connection of a selected generator to the system, of a single synchronizing means for said generators, a transfer relay for each generator, a main switching means for each generator for connecting it to the system, means operated from said remote selecting apparatus for closing the transfer relay of the selected generator, means controlled by the transfer relay for connecting the synchronizing means to the selected generator for bringing the same to synchronism, means controlled by the synchronizing means through the selected transfer relay for closing the corresponding main switching means, and means responsive to said selecting apparatus and independent of the transfer relay and synchronizing means for maintaining the main switching means closed.

ERICK PEARSON. 

